The present invention relates generally to hitches, and more specifically to a ball hitch for an implement drawbar of an agricultural vehicle.
U.S. Pat. No. 3,493,252 describes a ball and socket joint for a three point hitch of a tractor in which the drawbar is formed with a part-spherical socket which receives a part-spherical ball having a central bore, the latter, in use, receiving a coupling pin of a trailer. Because the diameter of coupling pins can vary, the ball is made in such a manner that it can be replaced by another of different inner diameter. In particular, part of the spherical surface of the ball is cut away to provide a portion of gradually reduced radius terminating at a radial face so that the ball may be inserted in a complimentary socket and prevented from being removed when it is turned to another position in the socket.
Though such an arrangement allows the ball to be replaced by another when it is worn or to adapt the joint to a different size of coupling pin, it does not allow for the fact that the part-spherical surface of the drawbar is prone to wear and its replacement is complex and costly. It would be very advantageous to have a ball hitch that avoids the problems mentioned immediately above.